What is the best solid state amplifier you have ever heard?

What is the best solid state amplifier you have ever heard?
ricred1 asks:
How do you isolate the amplifier? It's a system and every component, including the room impacts the sound.

Well the customary method is you disconnect it and swap it out with another amplifier. Just be sure to swap only the amp. You must use the same power cord, and cables, and cones, and even the same fuse if an aftermarket fuse is involved. Otherwise if you change the amp and the power cord, or cables, or anything else, then you will never know for sure how much of what you're hearing is the amp or something else. Changing only the one component allows you to hear differences due to that one component and that one component only.

Not only amplifiers, but every other component as well. That is how we do it. It is in fact what every review ever written is based upon. If you want to learn more about this and other essential elements of audio I highly recommend Robert Harley's book The Complete Guide to High End Audio. 
Luxman 509X. Incredible. Do not WANT to hear the M-900U/C-900U which is the Luxman combo that is appreciably better than the 509X. Supposedly the 509X is 90% of this top combo;

The engineering that went into the 509X receives maximum applause from me. 

+1 millercarbon

Someone posted a thread titled the best sounding integrated you’ve ever heard and akg_ca was somehow able to provide an answer, sans the unnecessary diatribe.

Best solid state amp I’ve heard was a Goldmund.
second on the M-900u over Dag S250 which i recently owned. tube was Ref 75se. the luxman was superior to the other two imho but would be extremely happy with any of them